Monsoon likely to set over Kerala on June 6, says IMD

The southwest monsoon is likely to be slightly delayed and will set over Kerala on June 6, with a model error of +/- 4 days, the India Meteorological Department (IMD) announced today.

The onset of the monsoon over Kerala marks the start of the rainy season in India and, as it progresses northward, relief from the scorching summer temperatures is expected over the region.

IMD said conditions were becoming favourable for the advance of southwest monsoon over the southern part of Andaman Sea, Nicobar Islands and adjoining southeast Bay of Bengal during May 18-19.

IMD has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards. An indigenously developed state of the art statistical model with a model error of four days plus or minus is used.

The six predictors used in the models are; Minimum Temperatures over North-west India; Pre-monsoon rainfall peak over south Peninsula; Outgoing Longwave Radiation (OLR) over the South China Sea; Lower tropospheric zonal wind over southeast Indian ocean; Upper tropospheric zonal wind over the eastern equatorial Indian Ocean and OLR over the south-west Pacific region.

IMD’s operational forecasts of the date of monsoon onset during the past 14 years (2005-2018) had proved to be correct except in 2015.

In the year 2014, the onset date forecast was June 6 but the monsoon arrived a day earlier on June 5. In 2015 the onset prediction was June 5 but the rains broke over Kerala on May 30. In 2016, the onset forecast was June 8 but the monsoon began on June 7. In 2017, it arrived on May 30 as predicted. In 2018, also IMD correctly predicted the monsoon arrival on May 29.

“Past data suggests that there is no association of the date of monsoon advance over the Andaman Sea either with the date of monsoon onset over Kerala or with the seasonal monsoon rainfall over the country,” a press release from IMD added.